testing: restore some testing for i686

testing: restore some testing for i686

The commit 4f9a8315e6 (gitlab-ci.d/crossbuilds: Drop the i386 system
emulation job) was a little too aggressive dropping testing for 32 bit
system builds. Partially revert but using the debian-i686 cross build
images this time as fedora has deprecated the 32 bit stuff.

As the SEV breakage gets in the way and its TCG issues we want to
catch I've added --disable-kvm to the build.

Reported-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240705084047.857176-3-alex.bennee@linaro.org>